Piano sounding board



Nov. 18, 1969 M. A. HAERICH 3,473,634

' PIANO SOUNDING BOARD Filed Nov. 28. 1967 INVENTOR. MILTON A. HAERICH ATTORNEYS United States Patent 3,478,634 PIANO SOUNDING BOARD Milton A. Haerich, 1033 Jamaica Court, Aurora, Colo. 80010 Filed Nov. 28, 1967, Ser. No. 686,100 Int. Cl. Gc 3/06 US. Cl. 84-493 3 Claims ABSTRACT OF THE DISCLOSURE This invention relates to an improved piano sounding board comprising a sandwich-like laminate made up of spaced, substantially-parallel strips of sheet material interconnected by corrugated strips that cooperate to produce a series of roWs of vertically-disposed individual cells overlaid both top and bottom by plastic sheets bonded thereto so as to produce a multiplicity of sealed individual sound-reverberating air chambers.

For well over a hundred years, the standard piano sounding board used to amplify the vibrating frequencies of the piano strings in both upright and grands has been made of carefully-seasoned wood panels. Probably the main deficiency present in a wooden sounding board is its inherent inability to provide the desired degree of sound amplification. From the standpoint of the user, however, certain other deficiencies assume greater significance. Among the latter is the pronounced tendency for a wooden sounding board to dry out, crack or warp under the influence of heat and high and low humidity. When this occurs, about the only real solution is to replace the defective sounding board with a new one, this being an expensive proposition.

Repeated efforts have been made over the years to overcome these difficulties but, so far, none have proved particularly successful. For example, sounding boards made of sheets of wood held in spaced relation by spacers therebetween were tried around the turn of the century in an effort to reduce the metallic sound resulting from the use of metal string frames; however, these sounding boards possessed the same deficiencies as any wooden sounding board used in the past. Hollow metal resonance chambers have also been used for the purpose of amplifying the tonal characteristics of certain notes. Obviously, such chambers did not crack and Warp; but, unfortunately, they had to be used in addition to a conventional wooden sounding board and, therefore the overall problem was not solved.

Several early attempts were made to improve both the sound-amplifying and strength characteristics of piano sounding boards by corrugating the surface thereof so as to produce a greater surface area. One such sounding board was made of corrugated metal while another was, presumably, made of wood. Neither, however, resulted in the compartmentalization of the resonating surface into individual air columns.

Probably the closest approach to the sounding board of the instant invention took the form of a fiat or slightly arched wooden board having a corrugated member attached to the upper surface thereof so as to produce a plurality of longitudinally-extending open-ended air columns. Actually, one such structure was designed to provide more surface area to the sounding board while retaining the required stiffness due to elimination of the usual cross braces or stifieners ordinarily used. No mention was made of any increased resonance because of the open-ended air columns, if in fact, any resulted.

Another similar structure used an arched or crowned sheet of wood overlaid with a corrugated material on the upper surface and with ribs on the underside that inter- 3,478,634 Patented Nov. 18, 1969 sected the corrugations and, theoretically, cooperated therewith to compartmentalize the board surface into a checkerboard pattern of flexible diaphragms. Here again, no mention was made of any increased resonance due to the presence of the elongate open-ended air columns formed between the arches of the corrugations and the panel upon which the corrugated material is attached. Also, these last-mentioned units still retain the basic wooden sounding board panel which is as susceptible to cracking and warpage as it ever was.

It has now been found in accordance with the teaching of the instant invention that a novel and improved piano sounding board obviating the aforementioned shortcomings of the wooden sounding board while possessing substantially enhanced sound amplification properties can be made by laminating between two sheets of plastic material a vertically-celled honeycomb element which, when so laminated, produces a plurality of closed vertical air columns. The resulting unit is extremely rugged and virtually unaffected by heat or humidity. It is also quite inexpensive and easy to fabricate in various shapes necessary to fit into the different types and styles of pianos. Most important, the vibrating air columns reproduce the piano tones, their harmonics, etc. as faithfully as a wooden sounding board; yet, amplified two or more times that of any of the prior art sounding boards.

It is therefore, the principal object of the present invention to provide a novel and improved sounding board for pianos and other stringed instruments of similar design.

A second objective of the invention herein disclosed and claimed is to provide a unit of the type aforementioned that possesses substantially improved sound amplification characteristics.

Another object is the provision of a sounding board for pianos and the like that is completely unaffected by changes in temperature and humidity within the ranges to which such an instrument is subjected under conditions of normal use.

Still another objective is to provide a sounding board that can be simply and easily adapted for use in any of the commonly used types and styles of pianos.

An additional objective is to provide a stringed instrument sounding board that is extremely strong and easily capable of withstanding the stresses to which a piano sounding board is ordinarily subjected.

Further objects are to provide a sounding board for pianos that is easy to fabricate and install, is inexpensive, versatile and lightweight, and one that faithfully reproduces the tones, overtones, harmonics and the like generated by the vibrating strings.

Other objects will be in part apparent and in part pointed out specifically hereinafter in connection with the description of the drawings that follows, and in which:

FIGURE 1 is a top plan view of the sounding board of the present invention cut in a shape suitable for use in a grand piano;

FIGURE 2 is a fragmentary top plan view, greatly enlarged, showing the sounding board with the top layer of the laminate removed to expose the interior honeycombed cellular structure; and,

FIGURE 3 is a fragmentary section taken along line 33 of FIGURE 2.

Referring now to the drawings for a detailed description of the present invention and, initially, to FIGURE 1 for this purpose, reference numeral 10 has been employed to designate the sounding board in its entirety and it is shown as it might be shaped for use in a grand piano, the latter having been indicated in broad outline by dotted lines at 12. The strings also shown in dotted lines at 14, of course, extend therebeneath where their vibrations can be picked up and amplified by the sounding board.

The particular shape shown in FIGURE 1 has no significance and many other configurations could be used with equally good results. As a general rule, the shape of the sounding board will be the same as that of the conventional wooden sounding board it is designed to replace. The unit is, likewise, not limited to use in any particular style of piano, i.e. grand, upright, studio, spinet, etc., in fact, it can be used to advantage in other stringed instruments of the same general characteristics like celestas, clavichords, virginals and harpsichords.

Next, with reference to FIGURES 2 and 3, it will be seen that the sounding board is actually a laminate consisting of a honeycomb core indicated in a general way be numeral 16 and which is covered both top and bottom by plastic sheets 18 and 20 that are bonded permanently to said core. Core 16 is preferably fabricated from strips of heavy Kraft paper and comprises a plurality of elon' gate planar strips 22 about one-half inch wide arranged in substantially equally-spaced parallel relation and interconnected at longitudinally-spaced intervals by corrugated strips 24 of the same width that have somewhat of a sine wave shape. These planar and corrugated strips are attached to one another at the nodes of the latter by suitable adhesives. The resulting core structure is one having a series of parallel rows made up of isosceles-shaped triangular cavities about a quater inch from base to apex,

These cavities are then closed, both top and bottom, by plastic sheets 18 and 20 which are laid on the surfaces of the core and permanently bonded thereto with appro priate adhesives well-known in the art. Actually, a satisfactory bond can be produced with some plastic sheet materials by painting the surface thereof to be bonded with an organic solvent such as acetone and, while the surface thus painted is still soft, applying the sheet to the core.

Regardless of the methods and materials used to fabricate the sounding board, the resulting laminate comprises a great number of vertically-disposed individually-sealed air columns 26 which respond to the vibrations induced therein by the sound waves generated in the string vibrating therebeneath to reproduce the tones of the strings faithfully and without distortion amplified to a level over twice that of a conventional wooden sounding board. It

has been found that an overall thickness of between about one-quarter and one-half inch is preferable for the sounding board of the present invention. The top and bottom sheets should be relatively thin on the order of A inch or less as the portions thereof that close the ends of the air columns must 'be capable of vibrating in the manner of the skin on a drum in order to produce the desired sound amplification. As illustrated in FIGURES 2 and 3, the unit is shown about twice its actual size.

What is claimed is:

1. The sounding board for pianos and the like which comprises: a honeycomb core covered both top and bottorn by relativelythin flexible plastic membranes that seal the ends of said cells and cooperate therewith to define a plurality of individual miniature drum-like elements responsive to the presence of a vibrating string in close proximity thereto and adapted to amplify the sound generated by the latter and wherein the core comprises a series of essentially-straight paper strips held in spaced substantially-parallel relation by corrugated paper strips passing therebetween and fastened thereto at the points of tangency.

2. The piano-sounding board as set forth in claim 1 in which: the core is formed from strips of paper and the membranes comprise thin sheets of flexible plastic material adhesively-bonded to said core.

3. The piano-sounding board as set forth in claim 1 in which: the straight and. corrugated strips cooperate to define generally isosceles-shaped triangular cells.

References Cited UNITED STATES PATENTS 873,949 12/1907 Knight 84-196 910,632 1/1909 Zinco 84-196 X 2,992,695 7/1961 Everitt 181-31 3,111,187 11/1963 Barlow 181-31 X 3,347,335 10/1967 Watters et a1. 181-31 X 3,380,206 4/1968 Barnett 181-33 RICHARD B. WILKINSON, Primary Examiner JOHN F. GONZALES, Assistant Examiner 

